Method and apparatus for minimizing combustible gas contents of engine exhaust gases



Sept. 8, 1964 1 5m M? 3m mm s M. J. TAUSCHEK ETAL METHOD AND APPARATUS FOR MINIMIZING COMBUST GAS CONTENTS OF ENGINE EXHAUST GASES Filed Oct. 17. 1960 COMPEL-550B COMPRESSOR INTAKE Tia/20771.5 ACCELEBA 7'08 PEDAL PREJSUKE p.11. 05587- Cl/M/W/M sept- 8, 1964 M. J. TAUSCHEK ETAL 3,

METHOD AND APPARATUS FOR MINIMIZING COMBUSTIBLE GAS CONTENTS OF ENGINE EXHAUST GASES Filed Oct. 17, 1960 4 Sheets-Sheet 2 gummy" P 1964 M J. TAUSCHEK ETAL 3,147,588

METHOD AND APFARATUS FOR MINIMIZING COMBUSTIBLE GAS CONTENTS OF ENGINE EXHAUST GASES Filed QGC- 17. 1960 4 SheetsSheet 3 MAX J. 77105045? ED55197 E. (l/MM/lVS P 3, 1964 M. J. TAUSCHEK ETAL 3,147,588

METHOD AND APPARATUS FOR MINIMIZING COMBUSTIBLE Filed Q01 17, 1960 GAS CONTENTS OF ENGINE EXHAUST GASES 4 Sheets-Sheet 4 2 A12 w {m V w j, m r: N R

o V EXHAU$T GASEi EX A05 EXHAUST ma 22 cwses E- L E ME MAX J. 721/5045? P0554 7: 5. Cl/MMl/l s United States Patent Ohio Filed Oct. 17, 1960, Ser. No. 63,026 8 tClairns. (Ci. 60-30) This invention relates to the reduction of combustible materials in exhaust gases from internal combustion engines and the like to make possible the release to the atmosphere of exhaust gases free from irritants, smog producing ingredients and poisonous compounds. Specifically, the invention relates to the burning of combus tibles and exhaust gases from internal combustion engines before releasing the exhaust gases to the atmosphere and while using the heat content of the gases for enhancing the burning operation.

While this invention will hereinafter be specifically described as embodied in the cylinder block of an internal combustion engine, it should be understood that the method and apparatus of this invention are generally useful for completing the combustion of unburned materials in exhaust or waste gases and, therefore, the invention is not limited to the preferred herein described specific embodiments.

It is well known that the smog problems are largely caused by exhaust emissions of automobiles and the like because the vehicles discharge appreciable quantities of carbon monoxide and unburned hydrocarbons. To efiiciently remove these noxious ingredients of exhaust gases,

'it is highly desirable to preserve the heat energy of the gases as they exhaust from the cylinder exhaust openings so that the gases may be mixed with air in a manifold burner or catalytic converter and reacted without the requirement for independent ignition means, although ignition means may be provided to initiate reaction conditions.

According to this invention, internal combustion engines operating on an Otto cycle are supplied with air to burn the combustibles in the exhaust gases thereof in such a manner as to cause auto ignition of the initially existing exhaust gas increment before it cools down by mixing with subsequent exhaust gas increments. The subsequent increments of exhaust gases expand adiabatically in the engine cylinder and normally cool down below temperatures for maintaining combustion of their combustible content. However, these subsequent increments are flowed into the burning initially exhausted gas increments and are heated by these burning gases to again raise their temperatures to a point sufiiciently high for maintaining combustion. The air feed is regulated automatically in proportion to the pressures of the succeeding exhaust gas increments to supply just enough oxygen for completing combustion. For highest efiiciency, the point of air introduction should be as close as possible to the initial exiting port from the engine cylinder.

In exhaust valve equipped engines the air introducing port or orifice can be immediately upstream from the valve seat, at the valve seat, at the valve head, or immediately upstream from the valve head.

' It is then a feature of this invention to efficiently burn the combustible content of internal combustion engine exhaust gases by introducing just enough air into the initially exiting gases from the engine cylinder while they are still hot enough to cause auto ignition, to then feed a mixture of air and the subsequent exiting gases to the burning gases to raise the mixture to ignition temperatures, and to then burn the mixture before releasing it to the atmosphere.

Another feature of the invention is to add air to internal combustion engine exhaust gases immediately adjacent the initial exhaust port from the engine cylinder before the initial increment of exhaust gases has cooled by mixing with subsequent exhaust gas increments to effect auto ignition of this initial increment for raising the temperature of succeeding exiting exhaust gas increments to maintain combustion thereof, and to control the air supply to the initial and succeeding gas increments as a function of gas flow rate.

Another feature of the present invention is the provision of means for introducing air into exhaust gases adjacent the cylinder exhaust valve opening in proportions directly related to the amount of exhaust gases issuing from the exhaust valve opening whereby eflicient burning of the combustible content of the exhaust gases is ensured.

A still further feature of the present invention is the provision of efiicient means for causing air to flow into and mix with exhaust gases adjacent the cylinder exhaust opening in dependent relationship to the flow of exhaust gases through said means.

It is therefore an object of this invention to provide an efiicient, and inexpensive and safe operating device for reducing the combustible content of exhaust or waste gases to minimize the harmful effects of discharge of the gases into the atmosphere.

Another object of this invention is to provide improved methods and means for minimizing the combustible contents of exhaust gases by advantageously employing thermodynamic phenomenon occurring in internal combustion engines.

Still another object of the present invention is to utilize the high temperature of exhaust gases at the instant they emerge from the cylinder exhaust valve opening to support combustion of the combustible content in the exhaust gases.

A still further object of the present invention is to utilize the high temperature conditions of exhaust gases first emerging from the cylinder exhaust valve opening to ignite the combustible content of the exhaust gases when mixed with air adjacent the exhaust valve opening.

A still further object of the present invention is to employ the high temperature gases first emerging from the cylinder exhaust valve opening to burn part of the unburned combustible content of the exhaust gases first emerging from the exhaust valve opening when mixed with sufficient air to thereby create a mean temperature sufficient to burn the combustible content of the successive proportions of the exhaust gas volume subsequently emitting from the cylinder.

On the drawing:

FIGURE 1 is a schematic view of apparatus found useful in the practice of the present invention.

FIGURE 2 is an enlarged fragmentary view of an embodiment of an air supply system for the apparatus of FIGURE 1.

FIGURE 3 is a view in cross section of the exhaust valve seat of FIGURE 2.

FIGURE 4 is a plan view of the exhaust valve seat of FIGURE 3.

FIGURE 5 is a view in partial section of an alternative embodiment of the present invention.

FIGURE 6 is a schematic view showing the relationship of the exhaust manifold and cylinder block to the air supply system of the embodiment of FIGURE 5.

FIGURE 7 is a pressure-volume diagram of a typical spark ignition internal combustion engine.

FIGURE 8 is a temperature-pressure diagram illustrating the changes in these conditions as the exhaust gas flows from the cylinder into the exhaust manifold.

FIGURE 9 is a view illustrating an exhaust valve found useful in the practice of the present invention.

FIGURE 10 is a modification of the valve of FIG- URE 9.

FIGURE 11 is a schematic illustration of the correlation of the air intake and exhaust gas flow conditions.

As shown on the drawing:

Briefly stated, the present invention relates to improved methods and means for minimizing the combustible gas content of the exhaust gases of internal combustion engines operating on the Otto-cycle.

The discussion now to follow will outline certain thermodynamic phenomena that occur in the cylinders of internal combustion engines as the phenomena relate to the flow of exhaust gases from the cylinder to the exhaust manifold.

As appears in FIGURE 7, which illustrates a typical pressure-volume Otto cycle diagram of a spark ignition internal combustion engine, in the compression process in the cylinder represented by line 1-2 the temperature in the cylinder increases to about 1000 F. During the combustion process, represented by line 2-3, the tempera ture to a peak level of approximately 4000 F. The temperature drops to approximately 2000 F., during the working stroke or expansion process represented by line 3-4. After the exhaust valve opens at 4, the gases exhaust through the exhaust ports into the exhaust manifold. The cylinder begins to blow down, represented by line 4-1, to exhaust manifold pressure Which is usually near ambient and of the order of, at 5, 15 lbs. p.s.i. For purposes of illustration, the pressure variant is illustrated within a range of about 15 p.s.i. to about 600 p.s.i. whereas the volume range is illustrated within a range of l to 7.

The instant the exhaust valve opens, the cylinder pressure begins to fall to exhaust manifold pressure. The first discrete increment or quantity of exhaust gas to leave the cylinder throttles through the exhaust valve opening and reaches the exhaust manifold at the manifold pressure but at a temperature substantially identical with that existing just prior to the first discrete increments leaving the cylinder. Meanwhile, the last discrete increment or quantity of exhaust gas to leave the cylinder is expanding adiabatically inside the cylinder according to the line 45 of FIGURE 7, prior to leaving the cylinder. This expansion occurs in accordance with the following relationship:

TP( =a Constant where,

T represents the absolute temperature P the absolute pressure, and n the apparent ratio of specific heats of the exhaust gases.

During the adiabatic expansion process, the last discrete increment or quantity of gas to leave the cylinder, prior to leaving, performs flow work on the gas ahead of it issuing from the cylinder. Thus the temperature of the last discrete increment of gas leaving the cylinder experiences a temperature drop which, when the last discrete increment of gas is exhausted into the manifold, may be as low as 1000 F. Intermediate discrete increments or quantities of gases leaving the cylinder during the exhaust process, first partially expand within the cylinder adiabatically with an attendant reduction in temperature and then throttle through the valve opening to the exhaust manifold with no great change in temperature.

The total volume of the mixture of gases in the exhaust manifold includes gas fractions at temperatures as high as 2000 F., others at temperatures as low as 1000 F. and other fractions having intermediate temperatures. The mean temperature of the increment mixture is about 1400 F. whereas a mean temperature of approximately 4 1600" F. is required before the ordinary combustible content of these gases will react with air.

Reference to FIGURE 8 will clarify the above concept. Area I indicates the conditions inside the cylinder, Area 11 indicates conditions at the exhaust port opening and Area III shows conditions in the manifold. Expansion in the cylinder takes place in Areas I and II and flow down the exhaust pipe in Area III.

As indicated by A, the gases are at approximately 4000 F. during the cylinder combustion phase. The first discrete increment of gas, B, exhausting through the exhaust valve opening at the instant the port is opened is at a temperature of approximately 2000 F. This discrete increment of gas is maintained at this temperature level as it flows into the exhaust manifold. The last discrete quantity of gas, C, leaving the exhaust cylinder is at approximately 1000 F. as a result of adiabatic expansion. Intermediate quantities of gas exhausting through the valve opening are at intermediate temperatures represented by the letter D. The mean temperature in the exhaust manifold, as indicated by the dash line, is approximately 1400 F., whereas the temperature required for combustion of the combustible content of the exhaust gases is approximately 1600 F. With the concentration of combustible content of exhaust gases ordinarily encountered in the spark ignition engine exhaust, the mean temperature thereof in the chart is below that required to sustain combustion thereof.

With the present invention, wherein chemically correct portions of air are mixed with each successive discrete increment of hot exhaust gases as they exhaust through the valve opening in accordance with the concepts outlined above, the mean temperature in the exhaust manifold may be raised above the level required to sustain auto-ignition of the combustible content of the gases. In acocrdance with the practice of the present invention, if the chemically correct proportion of air is mixed with the first discrete increment or quantity of exhaust gases exhausting from the exhaust valve opening, as appears in the chart of FIGURE 8, auto-ignition will occur since the temperature of the gases is above that required for reaction of the combustible content thereof with air. The temperature then of the burning gases will be above that of the exhaust gases as they issue from the valve opening. The increase in temperature of the first increment of gas exhausting from the valve opening will in turn be sufficient to raise the intermediate quantities of exhaust gases above the level required for auto-ignition of the combustible content thereof when mixed with air. Similarly the conditions established near the valve opening will be sufficient to raise the mean temperature adjacent the valve opening to sustain auto-ignition of the last discrete increment or quantity of exhaust gases leaving the exhaust port. The net result then will be to raise the mean temperature level of the exhaust gases in the manifold above that required for combustion of the combustible content of the exhaust gases when mixed with air. However, it is important to admit the correct amount of air at any given instant of time during the exhaust phase of the combustion cycle to complete the combustion of the exhaust gas with which that given volume of air mixes without including more air than is required, because this air, when passing into the manifold, will tend to reduce the mean temperature in the manifold. Thus the supplementary air must be added to each increment or discrete quantity of exhaust gases in chemically correct proportions as the exhaust gases issue from the port without mixing the various increments of exhaust gases of different temperature.

It is important therefore that the air be supplied to each discrete increment of the exhaust gases before there is any intermixture of the various increments of exhaust gases of different temperatures. For this purpose the air should be added to the exhaust gas increment as close as possible to the exhaust valve opening. In addition, the

air supplied to each discrete increment must be at a pressure at least equal to or above the exhaust pressure at the exhaust valve opening to avoid intermittent burning of the combustible content of the exhaust gases. It is preferable to heat the air thereby avoiding over-cooling of the initial exhaust gas increment discharging through the valve opening.

FIGURE 11 is a graph schematically illustrating the correlation between the air pressure in the air supply lines and the exhaust valve opening in terms of time. It is preferable to employ an air surge tank or accumulator and an orifice in the air supply system discharging into the exhaust gases when air is being introduced through the valve seat or valve head, whereby the air accumulator will exhaust or supply air as a function of the engine cylinder opening and closing operations. Thus as appears in FIGURE 11, with the exhaust valve closed, the pressure in the air supply source is above atmospheric pressure and increases over time until the instant the exhaust valve opens. At the instant the exhaust valve opens, the air is forced into the exhaust passage through the seat or valve by the pressure in the surge tank. The drop or reduction in air pressure is proportional to time as is the drop in pressure of the cylinder gases. Thus, each increment of gases, the first discrete increment, the last discrete increment and the intermediate increments, are supplied the required amount of air to support combustion of the combustible contents of these respective increments as a function of the exhaust gas flow conditions. Alternately, the air supply line opening may serve as the orifice adjacent the exhaust gas conduit for introducing air for mixture with the exhaust gases and the volume in the air supply line may operate as a surge tank.

As appears in FIGURE 2, it is desirable to introduce the air as close to the exhaust valve opening as possible. For this purpose, a conduit 12 is connected by a suitable fitting 13 to the cylinder head of each of the respective cylinders, as desired, for introduction therethrough to a passage 15 formed in the cylinder head 16. The valve seat 17 for the exhaust valve 18 defines with the cylinder head shoulder 19 an annular passage 20 communicating with the passage 15. The passage 20 communicates with a plurality of radial passages 21 which are concentrically aligned with the longitudinal axis of the sleeve or seat 17. For purposes of the embodiment of FIGURE 2, four such passages are shown, (FIGURE 4). A radial passage 22 and an annular groove 22a communicates each of the passages 21 with the interior of the seat 17 for introduction of air to be mixed with the exhaust gases as they flow from the cylinder in the direction indicated by the arrows in FIGURE 2.

As appears in FIGURES 3 and 4 the air ports 22 are spaced around the seat 17 to ensure uniform distribution of the air from the air source. The valve seat 17 if desired may comprise an inner valve receiving sleeve portion 17a concentric with the outer flanged portion 17b and is dimensioned to seat in the bore in the cylinder head 16, as shown in FIGURE 2. The inner surface of the valve seat is chamfered to provide the seat surface for the valve head 18a.

As appears in FIGURE 1, the system of the present invention is shown in combination with an 8 cylinder internal combustion engine. The engine, generally indicated by the numeral 23 includes a cylinder block 24 equipped with an intake manifold 25 receiving an airfuel charge from a carburetor 26 which in turn receives air from an air filter 27 and fuel from a fuel inlet (not shown). The engine 23 has a conventional engine driven water pump 28 circulating coolant through the jacketed walls of the cylinder block 24 and through a radiator 29. A radiator fan 30 mounted on a shaft driven by the engine and projecting from the pump 28 draws air through the radiator 29. A pulley (not shown) is also provided on this shaft in front of the pump 28.

An exhaust gas manifold 31 is mounted on each engine cylinder block 24 and has flanged nipples 32 mounted directly on the engine block to receive the exhaust gases directly from the exhaust valve ports of the engine.

Each manifold 31 has a single outlet 33 at the rear end thereof discharging through tubing 34 into a conventional exhaust gas muflier 35 and thence through the conventional tail pipe 36 to the atmosphere.

An air inlet 37 is provided at the front end of the engine adjacent the fan and delivers air to an engine driven compressor 38 that is driven through a belt (not shown) from the radiator fan shaft pulley. The compressor 38 has a single air inlet, as aforementioned 37, containing a throttle valve 39 operated by a rod 40 linked to the accelerator pedal 41 of the vehicle as illustrated in FIG- URE 1. The linkage is such that the throttle valve 39 is opened when the pedal 41 is depressed and closed when the pedal 41 is released so that air entering the compressor 37 is progressively throttled as engine load is decreased.

If desired, the positions of the manifolds 31 on the en gine block 24 may be reversed from the rear illustrated outlet positions and the outlets 33 may be at the front ends of the engine blocks or one manifold 31 may have its outlet 33 at the front end and the other manifold (not shown) may be positioned with its outlet 33 at the rear end of the engine.

The compressor 33 is connected by conduits 42 to a plurality of air sump or accumulator tanks 43 from which a plurality of branch lines 12 through extend to connect each of the cylinder head passages 15 with the air supply as appears in FIGURE 1. For the engine illustrated in FIGURE 1, the line 12 would connect one of the cylinders, 12a to another of the cylinders and 12b and 120 to the remaining two cylinders. For purposes of illustration only one of the cylinder blocks is shown; however, it will be appreciated that similar branch conduits may extend to the cylinder heads on the opposed cylinder block (not shown).

Thus, in the present compressor arrangement, the compressor 38 will supply air to the accumulators 43 as a function of engine operating conditions. The delivery of air to the accumulators 43 is therefore influenced only by throttling of the air inlet in response to engine fuel setting and by the speed of the compressor 38 in response to engine speed. In accordance with this invention, throttling of the air inlet 37 may also be automatically accomplished by referencing the throttle valve 39 to intake manifold pressure so that the valve will open on increases in intake manifold pressure and close as the manifold vacuum increases. In this arrangement likewise, the air inlet throttling will be responsive to engine load, but actuation will be automatically effected through vacuum lines instead of through the accelerator pedal linkage.

Pressure in the accumulators 43, lines 12 through 120 and the passages in the valve seat will be maintained above atmospheric level as indicated in FIGURE 11. With the exhaust valve closed, pressure will build up in the accumulators 43 and lines and passages connected thereto, air flow being blocked by the valve in the sea-t. The air pressure in the accumulators 43 will increase as shown by the curve in FIGURE 11. At the instant the exhaust valve leaves its seat and uncovers the apertures 22, air is supplied to the first discrete increment or quantity of exhaust gases leaving the cylinder through the exhaust valve opening. The orifices or ports 22 limit the air flow through the seat 17 to a relatively low value when the exhaust valve is fully opened and the residual gases, i.e., the last discrete increment of exhaust gases and intermediate increments thereof, -are being exhausted from the engine cylinder by piston displacement. The orifice also permits the air surge tank or accumulators 43 to charge to a relatively high pressure when the exhaust valve is closed and the orifices 22 are blocked thereby. Thus a greater quantity of air under a higher pressure is supplied throughthe orifices for mixture with the first discrete increment or quantity of exhaust gases flowing through the valve opening when the valve is first opened. The minimum amount of air is introduced through the orifices 22 for mixture with the last increment or quantity of exhaust gases leaving the cylinder and intermediate quantities of air are introduced through the orifices under intermediate pressures for a mixture with each intermediate increment of exhaust gases issuing from the exhaust valve port. As aforementioned, the air pressure is equal to or above the exhaust pressure for each increment of exhaust gas leaving the exhaust valve port, and passage of the air through the valve seat tends to heat the air to avoid over-cooling of the initial increment or quantity of exhaust gases leaving the exhaust valve opening.

Thus the flow of exhaust gases cooperate with the pressure flow of air to ensure proper mixing of the proper proportions of air and exhaust gases on an incremental basis over time.

If desired, the air surge tanks may be eliminated and the branch conduit 12 through 120 connected directly to the compressor 38 whereby the air will be supplied as a function of engine operating conditions and the volume of the supply line and orifices 22 will be sufiicient to control the air and exhaust gases and quantities thereof mixing at any increment of time.

The air surge tanks thus blow down in the same manner as the engine cylinder, starting at the instant the exhaust valve leaves its seat, and, therefore, air supply rate is substantially similar to exhaust gas blow down flow rate through the valve openings.

An alternative embodiment of the present invention is shown in FIGURE wherein the cylinder head 16 is provided with a conventional exhaust valve 18. Disposed between the cylinder head 17 and the exhaust manifold 31 may be a longitudinally extending air duct 45 which is connected by a conduit 46 to the compressor line 42 by a suitable fitting (not shown). A surge tank and orifice are not needed in the embodiment employing the aspirator assembly hereinafter described. Adjacent each cylinder exhaust discharge port is a passage 47 communicating the discharge port with the air accumulator chamber 45. The passage 47 is secured in place preferably by a collar 48 secured to the cylinder head as by bolts 48a. Each of the cylinder head exhaust ports are counterbored as at 48b to receive a venturi nozzle member 49 of an aspirator assembly securely seated against the shoulder 50 provided by the counterbore 48b in the cylinder head and a retaining ring 51 seated in a groove formed in the cylinder head. Extending through the accumulator chamber 45 adjacent to and preferably coaxially aligned with the exhaust port opening is a guide member 52 adapted to receive a variable induction tube 53 flanged as at 54 for securing the induction tube to the manifold exhaust gas inlet 32 as by bolts 55. Secured in the induction tube or connected thereto is a venturi nozzle member 56 which is coaxially aligned with the exhaust gas nozzle 49. The nozzle 49 is preferably positioned into the exhaust passage for introduction of air into the counterbore adjacent the nozzle 49 so that approximately a chemically correct amount of air is added by aspiration to the exhaust gases to consume the residual unburned combustibles therein. The nozzle 49 is provided for the purpose of imparting a higher velocity to the exhaust gases, thereby inducting or aspirating the air in the counterbore through the venturi nozzle 56 for mixture thereof with the exhaust gases in the induction tube. If air chamber 45 is positioned between the manifold and the cylinder block as shown, preheating of the air in the accumulator chamber occurs, and the heat radiated from the induction tube contribtue to the preheating of the air.

For initiating combustion of the combustible content of the exhaust gas-air mixture in the induction tube, auxiliary ignition means may be employed, if desired. For this purpose, any type of ignition means, such as a spark plug, or conventional electrodes 59 positioned in the induction tube passageway having leads 57a and 57b which may be appropriately coupled into the circuit of the ignition system of the vehicle in which the apparatus is employed (not shown).

In operation, when the exhaust valve opens, the first increment or quantity of exhaust gases emanating from the cylinder, as shown by the arrows, flows through the induction nozzle and has a higher velocity imparted thereto. The induction tube 53 is positioned so that the exhaust gases flow from the nozzle 49 into the nozzle 56 of the induction tube, and, in passing through the space between the nozzle 49 and nozzle 56 aspirates the correct amount of air from the counterbore in the cylinder head 16 for reacting the combustible content of the exhaust gases mixed therewith in the induction tube 53. The burning gases then flow through the induction tube 53 into the exhaust manifold 31 for subsequent discharge through the tail pipe. Similarly the last increment of exhaust gases in the cylinder exhausts through the nozzles 49 and 56 aspirating the correct proportion of air required for reaction with the combustible contents contained therein, as do the intermeditae increments of exhaust gases flowing from the cylinder. The initial increment of exhaust gases flowing from the cylinder raises the temperature in the induction tube to a level sufficient to support combustion of the gases subsequently emerging from the cylinder, and, in turn, each of these increments collectively and sequentially maintain the temperature in the induction tube 53 at a level suflicient to permit burning of the combustible content of the next succeeding increment of exhaust gases therein. The nozzle 49 imparts a sufiicient velocity to the exhaust gases to prevent flow thereof through the counterbore and into the air chamber 45. The air is maintained under pressure to cooperate with the nozzle 49 to assure that burning in the counterbore and accumulator 45 does not take place.

Thus the temperature level maintained in the manifold is above the level required for combustion of the combustible content of the exhaust gases and the adjustability of the variable induction tube permits proper positioning thereof with respect to the fixed nozzle 49 for the purpose of insuring the correct proportions of air and gas mixture in the induction tube 53.

Each of the increments of exhaust gases are thereby provided with sufficient air in chemically correct proportions to each increment of exhaust gas issuing from the port to ensure substantially complete combustion of the combustible content contained in the respective increments. Thus it is desirable to introduce the air for mixture with the exhaust gases at a point as close as possible to the exhaust valve outlet.

As appears in FIGURES 9 and 10, the air may be introduced through the valve 18 for supply thereof adjacent the valve opening in the cylinder head.

In FIGURE 9, a valve is shown extending through the valve guide 60 apertured as at 61 in communication with the passage 15 in the cylinder head 16. The valve stem is provided with a radial passage 62 communicating with an axially aligned passage 63 plugged as at 64 which communicates with a plurality of radiating branch passages 65 for introduction of air adjacent the valve opening of the cylinder. The passages 65 may be four in number, each positioned from the other and formed below the valve head. The air supply passage 15 and guide passage 61 are formed relative to the passage 62 so that they are out of communication when the valve head 18a is seated in the valve seat. When the valve head moves to open the valve opening, passage 62 is aligned with passage 61 in the guide 60 and permits flow of air through the passage 63 and radial passage 65 for mixture thereof with the exhaust gases.

Alternatively, as appears in FIGURE 10, the valve 18 may be provided with the branch passage 62 and main passage 63 which communicates with radially extending passages 66 formed in a similar manner to the passage 65 of FIGURE 9, but in the valve head 18a. The operation of the system where the air supply passages are formed in the valve per se operates on principles similar to those above described With respect to the apparatus of FIGURE 5.

Thus it will be appreciated that by employment of the present invention, the combustible content of exhaust gases may be substantially eliminated. In accordance with the practice of the instant invention, the available combustion heat that exists after each combustion cycle in the engine cylinder is employed to mix chemically correct proportions of air with each increment of exhaust gases, and each increment of burning exhaust gases promotes further burning of each subsequent increment of exhaust gases. The air supply flow characteristics and quantities are dependent upon the flow rate and quantities of exhaust gases discharging from the exhaust valve. The air is introduced for mixture with the exhaust gases adjacent the exhaust valve opening where a suitable environment in terms of temperature is present to ensure burning of the combustible content of the exhaust gases. Furthermore by appreciating and recognizing certain. thermodynamic phenomena that occur in the cylinder combustion cycle and by taking advantage of these phenomena, we maintain the mean temperature of the exhaust gases, when considered as a whole, above the level required to sustain auto-ignition of the combustible content of the exhaust gases when mixed with the proper and correct proportion of air.

It will be understood that other modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. In an internal combustion engine, a working cylinder, an exhaust valve closing ofl? said cylinder and operable periodically to vent exhaust gases from said cylinder at pressures decreasing from cylinder pressures, air directing means located at said exhaust valve to direct air at the exhaust gases being vented from said cylinder, air supply means connected to said air directing means to deliver air thereto, said air supply means providing a maximum air pressure in said air directing means during initial opening of said exhaust valve while providing air in a quantity suflicient to support combustion of the combustibles in said exhaust gases, said air supply means providing air at pressures decreasing with said exhaust gas pressure whereby the maximum burning of said combustibles will be effected as venting of the exhaust gases proceeds.

2. In an internal combustion engine, a working cylinder, an exhaust valve closing 011 said cylinder and operable periodically to vent exhaust gases from said cylinder and pressures decreasing from cylinder pressures, a valve seat insert ring seating said exhaust valve and having passages therein arranged to direct air at the exhaust gases being vented upon unseating of said exhaust valve, air supply means arranged to deliver air into said passages in said valve seat insert ring, said air supply means providing a maximum air pressure in said passages during initial opening of said exhaust valve While providing air in a quantity sufficient to support combustion of the combustibles in said exhaust gases, and said air supply means providing air at pressures decreasing with said exhaust gas pressure whereby the maximum burning of said combustibles will be eifected as venting of the exhaust gases proceeds.

3. The structure of claim 1 in which said air supply means is an air accumulator tank.

4. In an internal combustion engine, a working cylinder, an exhaust valve closing off said cylinder and operable periodically to vent exhaust gases from said cylinder at pressures decreasing from cylinder pressures, said exhaust valve having passages therein arranged to introduce air into the exhaust gases being vented from said cylinder immediately upon opening of said exhaust valve, air supply means connected to said passages to deliver air thereto, said air supply means providing a maximum air pressure in said passages during initial opening of said exhaust valve While providing air in a quantity sufficient to support combustion of the combustibles in said exhaust gases, and said air supply means providing air at pressures decreasing with said exhaust gas pressure whereby the maximum burning of said combustibles will be effected as venting of the exhaust gases proceeds.

5. The method of reducing the combustible content of exhaust gases from an internal combustion engine cylinder which comprises directing an air stream at the exhaust gases leaving said cylinder before appreciable expansion of the exhaust gases occurs, the amount of air being sufficient to provide for combustion of the combustibles in the exhaust gases leaving the cylinder immediately at the time of exhaust but being insuificient to cool the exhaust gases below the auto ignition temperature of the exhaust gases, and continuing the supply of air to said exhaust gases at decreasing pressures as venting of the exhaust gases from said cylinder proceeds.

6. The method of reducing the combustible content of exhaust gases from an internal combustion engine cylinder which comprises building up air pressure in an air supply means while said cylinder is not exhausting gases, directing pressurized air from said air supply means at the exhaust gases at a maximum air pressure immediately upon initial venting of exhaust gases from said cylinder, the amount of air being sufiicient to provide for combustion of the combustibles in the exhaust gases leaving the cylinder immediately at the time of exhaust but being insuflicient to cool the exhaust gases below the auto ignition temperature of the exhaust gases, and continuing the supply of air from said air supply means to said exhaust gases at diminishing pressures as venting of said exhaust gases from said cylinder proceeds.

7. The method of claim 6 in which the decrease in pressure from said air supply means corresponds substantially to the decrease in pressure of exhaust gases from said cylinder.

8. The method of reducing the combustible content of exhaust gases from an internal combustion engine cylinder which comprises directing an air stream at the exhaust gases leaving said cylinder before appreciable expansion of the exhaust gases occurs, the amount of air being sufficient to provide for combustion of the combustibles in the exhaust gases leaving the cylinder immediately at the time of exhaust but being insufiicient to cool the exhaust gases below the autoignition temperature of the exhaust gases, and continuing the supply of air to said exhaust gases at decreasing rates corresponding to the decrease in rate of exhaust gases leaving the cylinder as venting of said cylinder proceeds, whereby the resultant mixture of air and exhaust gases provides substantially optimum conditions for autoignition of the combustibles contained in said exhaust gases.

References Cited in the file of this patent UNITED STATES PATENTS 1,731,222 Blair Oct. 8, 1929 1,802,469 Hofmann Apr. 28, 1931 1,873,119 Griswold Aug. 23, 1932 2,263,318 Tifit Nov. 18, 1941 2,295,436 Tendler Sept. 8, 1942 2,544,605 Mallory Mar. 6, 1951 2,819,704 Niederman Jan. 14, 1958 FOREIGN PATENTS 777,949 France Dec. 15, 1934 

8. THE METHOD OF REDUCING THE COMBUSTIBLE CONTENT OF EXHAUST GASES FROM AN INTERNAL COMBUSTION ENGINE CYLINDER WHICH COMPRISES DIRECTING AN AIR STREAM AT HE EXHAUST GASES LEAVING SAID CYLINDER BEFORE APPRECIABLE EXPANSION OF THE EXHAUST GASES OCCURS, THE AMOUNT OF AIR BEING SUFFICIENT TO PROVIDE FOR COMBUSTION OF THE COMBUSTIBLES IN THE EXHAUST GASES LEAVING THE CYLINDER IMMEDIATELY AT THE TIME OF EXHAUST BUT BEING INSUFFICIENT TO COOL THE EXHAUST GASES BELOW THE AUTOIGNITION TEMPERATURE OF THE EXHAUST GASES, AND CONTINUING THE SUPPLY OF AIR TO SAID EXHAUST GASES AT DECREASING RATES CORRESPONDING TO THE DECREASE IN RATE OF EXHAUST GASES LEAVING THE CYLINDER AS VENTING OF SAID CYLINDER PROCEEDS, WHEREBY THE RESULTANT MIXTURE OF AIR AND EXHAUST GASES PROVIDES SUBSTANTIALLY OPTIMUM CONDTIONS FOR AUTOIGNITION OF THE COMBUSTIBLES CONTAINED IN SAID EXHAUST GASES. 